Effects of the Non-Newtonian Viscosity of Milk Flow in the Breast Ductal System

2019 ◽  
Author(s):  
Jamasp Azarnoosh ◽  
Fatemeh Hassanipour
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Newtonian Fluid ◽  
Flow Properties ◽  
Newtonian Viscosity ◽  
Ductal System ◽  
Milk Flow ◽  
Clinical Investigations ◽  
Fluid Wall Shear Stress ◽  
The Impact

Abstract Numerical simulation of human milk flow inside the breast ductal system is carried out to investigate the impact of milk flow properties, specifically viscosity, on the flow regime. The geometry of the ductal system is assumed as a rigid body with six bifurcation levels. The vacuum pressure, obtained from clinical investigations, is applied as boundary conditions for numerical analysis. The simulations are performed by considering both Newtonian and Non-Newtonian milk flow properties. The streamlines of velocity fluid, wall shear stress, and milk flow expression for these two models are discussed. The results show that the non-Newtonian fluid has a higher magnitude of velocity compared to the Newtonian fluid, which leads to a greater amount of milk expression.

scholarly journals Investigations on the Impact of Using Elliptic Groynes on the Flow in Open Channels

2021 ◽  
Vol 27 (2) ◽  
pp. 44-58
Author(s):  
Ahmed M. Hussein AL‏-‏Sarefi ◽  
Riyadh Z. Azzubaidi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Good Accuracy ◽  
Open Channels ◽  
Bed Shear Stress ◽  
Cfd Model ◽  
Good Ability ◽  
Bed Slope ◽  
The Impact

This paper presents a numerical simulation of the flow around elliptic groynes by using CFD ‎software. The flow was simulated in a flume with 4m long, 0.4m wide, ‎and 0.175m ‎high ‎‎with a constant bed slope. Moreover, the first Groyne placed at 1m from the flow ‎‎inlet with a ‎constant the Groyne height of 10cm and a 1cm thickness, and the ‎width of Groynes equals ‎7cm‎. A submergence ratio of the elliptic Groynes of 75% was assumed, corresponding to a discharge of ‎0.0057‎m3/sec. The CFD ‎model showed a good ability to simulate the flow ‎around ‎Groynes with ‎ good accuracy. The results of ‎CFD software showed that when using double elliptic Groynes, the bed shear stress is decreased with the ‎increase in the spacing between Groynes, as well as and the best spacing between the double ‎elliptic Groynes is twice of the Groyne width. Moreover, the used number of Groynes has no ‎much ‎impact ‎on velocity and shear ‎stress values.

Vortex Dynamics in Sidewall Aneurysms: Hemodynamic Transition During Growth and Clinical Implications

2017 ◽  
Author(s):  
Trung Bao Le ◽  
Fotis Sotiropoulos
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Vortex Dynamics ◽  
Loading Condition ◽  
Aneurysm Rupture ◽  
Clinical Implications ◽  
Aneurysmal Wall ◽  
Flow Pulsatility ◽  
The Impact

Recent works have suggested that aneurysm size and shape might not be the only indicators to predict aneurysm rupture. Rather, the long-term interaction between hemodynamics and aneurysmal wall via the loading condition (i.e shear stress and pressure) may also be important. In this work, we investigate the impact of flow pulsatility on the hemodynamic patterns on aneurysmal dome during its growth using numerical simulation.

An experimental and numerical investigation on impact spot welding of metallic plates using gas mixture detonation technique

2020 ◽  
pp. 146442072098232
Author(s):  
Sedigheh Hosseinzadeh ◽  
Hashem Babaei ◽  
Tohid Mirzababaie Mostofi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Plastic Strain ◽  
Spot Welding ◽  
Equivalent Plastic Strain ◽  
Welding Process ◽  
Gas Mixture ◽  
The Impact ◽  
Base Plates ◽  
Metallic Plates

In this paper, the impact spot welding of metallic plates was investigated both experimentally and numerically using a single-stage gas mixture detonation apparatus. The impact spot welding process was carried out on aluminum alloy and steel materials using rigid steel projectiles. In this process, the mixture of oxygen and acetylene was detonated in a combustion chamber to launch the projectile. The masses of flat- and spherical-nosed projectiles were 270 and 230 g, respectively. The impact velocity was measured in all experiments. The cross-sections of the weld spots were inspired by a scanning electron microscope to assess the quality of welding. For several experiments, wavy interfaces were observed showing there is a good bonding. For numerical simulation of the process, Abaqus/Explicit software was used and the deformation and failure mechanisms of impact spot-welded specimens were further investigated. The Johnson–Cook thermoplasticity model along with its failure model was utilized to predict the behavior of metallic materials. The numerical simulation results were in good agreement with those obtained from experiments in terms of the deformation mode and failure pattern. The propagation of the wave on the surface of the flyer plate was further studied. The results showed that the stress waves start from the center and propagate to the corners of the plate. To numerically evaluate the welding quality, two parameters of the shear stress at the collision point as well as the equivalent plastic strain for the flyer and target plates were obtained in the numerical simulation. The numerical results showed opposite directions of shear stress for flyer and base plates at the contact point, which can be used as proof for good bonding. Besides, the magnitudes of the equivalent plastic strain for both flyer and base plates were higher than those reported values in the open literature that confirms successful welding.

WSS Investigation in Microfluidic FFS Channel at Re 500

2014 ◽  
Vol 487 ◽  
pp. 294-297 ◽  
Author(s):  
Zaliman Sauli ◽  
Vithyacharan Retnasamy ◽  
Steven Taniselass ◽  
Nor Shakirina Nadzri ◽  
Tan Hsio Mei ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Shear Stress ◽  
Stress Distribution ◽  
Wall Shear Stress ◽  
Newtonian Fluid ◽  
Microfluidic Devices ◽  
Wall Shear Stress Distribution ◽  
Wall Shear ◽  
Laminar Condition

Wall shear stress (WSS) is one of the important variables in microfluidic devices. In this paper WSS distribution for a microfluidic device in Forward Facing Step (FFS) configuration has been investigated using Reynolds number 500 and step height 1μm. Numerical simulation was performed usingAnsys-CFX software with the assumption of Newtonian fluid and laminar condition. The simulation result showed that wall shear stress distribution increased after the fluid passing through the step.

Numerical Simulation in Transient Flow of Non-Newtonian Fluid in Nozzles

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Azmahani Sadikin ◽  
◽  
Mohd Khairul Anam Mohd Bahrin ◽  
Azzura Ismail ◽  
Al Emran Ismail ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Newtonian Fluid ◽  
Transient Flow

Visualization of separation and reattachment in an incident shock-induced interaction

2021 ◽  
pp. 095441002098349
Author(s):  
Yun Jiao ◽  
Chengpeng Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shear Stress ◽  
Separation Bubble ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Bottom Wall ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Oil Flow

An experimental study is conducted on the qualitative visualization of the flow field in separation and reattachment flows induced by an incident shock interaction by several techniques including shear-sensitive liquid crystal coating (SSLCC), oil flow, schlieren, and numerical simulation. The incident shock wave is generated by a wedge in a Mach 2.7 duct flow, where the strength of the interaction is varied from weak to moderate by changing the angle of attack α of the wedge from 8° and 10° to 12°. The stagnation pressure upstream was set to approximately 607.9 kPa. The SSLCC technique was used to visualize the surface flow characteristics and analyze the surface shear stress fields induced by the initial incident shock wave over the bottom wall and sidewall experimentally which resolution is 3500 × 200 pixels, and the numerical simulation was also performed as the supplement for a clearer understanding to the flow field. As a result, surface shear stress over the bottom wall was visualized qualitatively by SSLCC images, and flow features such as separation/reattachment and the variations of position/size of separation bubble with wedge angle were successfully distinguished. Furthermore, analysis of shear stress trend over the bottom wall by a hue value curve indicated that the relative magnitude of shear stress increased significantly downstream of the separation bubble compared with that upstream. The variation trend of shear stress was consistent with the numerical simulation results, and the error of separation position was less than 2 mm. Finally, the three-dimensional schematic of incident shock-induced interaction has been achieved by qualitative summary by multiple techniques, including SSLCC, oil flow, schlieren, and numerical simulation.

Hybrid nanofluid flow over a stretched cylinder with the impact of homogeneous–heterogeneous reactions and Cattaneo–Christov heat flux: Series solution and numerical simulation

Heat Transfer ◽  
2021 ◽  
Author(s):  
Anthonysamy John Christopher ◽  
Nanjundan Magesh ◽  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Ravikumar Shashikala Varun Kumar
Keyword(s):  
Numerical Simulation ◽  
Heat Flux ◽  
Series Solution ◽  
Heterogeneous Reactions ◽  
Hybrid Nanofluid ◽  
Nanofluid Flow ◽  
The Impact

P3588The synergistic effect of NIRS-detected lipid-rich plaque and 5 different multidirectional wall shear stress metrics on human coronary plaque growth

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E M J Hartman ◽  
A M Kok ◽  
A Hoogendoorn ◽  
F J H Gijsen ◽  
A F W Steen ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Synergistic Effect ◽  
Coronary Arteries ◽  
Wall Thickness ◽  
Plaque Progression ◽  
Lipid Rich Plaque ◽  
Plaque Growth ◽  
Wall Shear ◽  
The Impact

Abstract Introduction Local wall shear stress (WSS) metrics, high local lipid levels (as detected by near-infrared spectroscopy (NIRS)), as well as systemic lipid levels, have been individually associated with atherosclerotic disease progression. However, a possible synergistic effect remains to be elucidated. This study is the first study to combine WSS metrics with NIRS-detected local lipid content to investigate a potential synergistic effect on plaque progression in human coronary arteries. Methods The IMPACT study is a prospective, single centre study investigating the relation between atherosclerotic plaque progression and WSS in human coronary arteries. Patients with ACS treated with PCI were included. At baseline and after 1-year follow-up, patients underwent near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) imaging and intravascular doppler flow measurements of at least one non-culprit coronary artery. After one month, a CT angiography was made. CT derived centreline combined with IVUS lumen contours resulted in a 3D reconstruction of the vessel. The following WSS metrics were computed using computational fluid dynamics applying the vessel specific invasive flow measurements: time-average wall shear stress (TAWSS), relative residence time (RRT), cross-flow index, oscillatory shear index and transverse wall shear stress. Low TAWSS is known as pro atherogenic, in contrast to all the other shear stress metrics, at which a high magnitude is pro-atherogenic. The arteries were divided into 1.5mm/45° sectors. Based on NIRS-IVUS, wall thickness change over time was determined and NIRS positive sectors detected. Furthermore, per vessel the shear stress was divided into tertiles (low, intermediate, high). To investigate the synergistic effect of local lipids on shear stress related plaque growth, wall thickness change over time was related to the different shear stress metrics comparing the NIRS-positive with the NIRS-negative sectors. Results 15 non-culprit coronary arteries from the first 14 patients were analyzed (age 62±10 years old and 92.9% male). A total of 2219 sectors were studied (5.2%, N=130, NIRS-positive) for wall thickness changes. After studying all five shear stress metrics, we found for TAWSS and RRT that presence of lipids, as detected by NIRS, amplified the effect of shear stress on plaque progression (see figure). Sectors presenting with lipid-rich plaque, compared to NIRS-negative sectors, showed more progression when they were exposed to low TAWSS (p=0.07) or high RRT (p=0.012) and more regression in sectors exposed to high TAWSS (p=0.10) or low RRT (p=0.06). Delta wall thickness vs shear stress Conclusion We presented the first preliminary results of the IMPACT study, showing the synergistic effect of lipid rich plaque and shear stress on plaque progression. Therefore, intravascular lipid-rich plaque (NIRS) assessment has added value to shear stress profiling for the prediction of plaque growth, leading to improved risk stratification. Acknowledgement/Funding ERC starting grant 310457

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